internal anatomy of the heart, internal view of the heart structures

Internal Heart Structures

Quizzes on Heart Chambers, Valves, and Blood Flow

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Introduction
Quizzes
Terms of Use
References and Attributions

Introduction

The heart primarily consists of four hollow chambers. There are two upper chambers, called the atria, and two lower chambers, called the ventricles. Large veins carry blood into the atria from all parts of the body. The blood then passes into the ventricles and is ejected into the large arteries that carry it away from the heart.

Blood flows into, through, and out of the heart due to pressure differences, moving from high-pressure to low-pressure areas. The heart valves regulate blood flow and ensure it moves in the correct direction.

Heart Chambers

Atria

The right atrium is the receiving chamber for deoxygenated blood returning from the systemic circulation and the heart tissues. A large vein, the superior vena cava, drains blood from the head, neck, upper limbs, and thoracic regions. A second large vein, the inferior vena cava, drains blood from the lower limbs and abdominopelvic regions. The left atrium receives oxygenated blood from the left and right lungs via the four pulmonary veins.

Ventricles

Blood from the right atrium enters the right ventricle. When the right ventricle contracts, it ejects deoxygenated blood into the pulmonary trunk. The blood then travels to the lungs through the left and right pulmonary arteries, which branch from the pulmonary trunk. The left ventricle receives oxygenated blood from the left atrium and pumps it into the systemic circuit via the aorta.

Internal Structures of the Heart – Labeling Activity

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Heart Valves

Atrioventricular Valves

The right atrioventricular (tricuspid) valve regulates blood flow between the right atrium and right ventricle. The left atrioventricular valve (bicuspid or mitral valve) controls blood flow between the left atrium and left ventricle. The flaps of the atrioventricular valves attach to strands of connective tissue called the chordae tendineae. These resilient, thin tendinous cords connect each flap to papillary muscles, which protrude from the ventricular walls. The chordae tendineae anchor the valve flaps so they cannot open into the atrium during ventricular contraction, preventing backflow of blood into the atria.

Semilunar Valves

The pulmonary semilunar (pulmonic) valve regulates blood flow between the right ventricle and the pulmonary trunk. When the ventricle relaxes, the chamber pressure drops, and blood flows back from the pulmonary trunk toward the ventricle. This reverse flow causes the valves to close, preventing blood from reentering the right ventricle. The aortic semilunar (aortic) valve regulates blood flow between the aorta and the left ventricle. When the left ventricle relaxes, ventricular pressure drops, and the backflow of blood closes the valve, preventing blood from flowing into the chamber.